Tag Archives: mdrx

The Hornady 6mm ARC for the Desert Tech MDRX

It seems all too frequent nowadays for a new cartridge to jump to the front of every blog, magazine, and ad campaign.
Ammunition manufacturers are always looking for the next best thing to sell. I cant blame them, and I’d much prefer they spend all the money on R&D so the rest of us don’t have to.
At the top of the ammunition game is the big red H that we have all come to know quite well. Hornady has brought some extremely popular cartridges to market in the recent past, the PRC family comes to mind, as does the revered 6.5 Creedmoor.
This year Hornady has again brought another impressive project to the shooting public, or at least legitimized an older one. The 6mm Advanced Rifle Cartridge (ARC) is that new product, and it looks to become as popular as it’s other red-tipped siblings.
The 6mm ARC is essentially a 6mm Grendel, but legitimized by Hornady’s production. It shares a few basic dimensions with the Grendel, but necked down to .243/6mm. It shoots heavy for caliber bullets in the 90-110 grain range, from a 7.5 twist barrel.
Hornady currently offers three different loads for the ARC, a 103 grain ELD-X in the Precision Hunter line, a 105 BTHP in the Black ammunition line, and a 108 grain ELD Match in their match ammunition line. In addition to these different ammunition lines, Hornady has also released loading dies, and components for loading the ARC.

Having seen many of these new cartridges come and go, I was cautiously optimistic for several reasons.
Just because it’s new doesn’t alway make it better, but I had long been considering a 6mm small frame AR cartridge like the Grendel or the 6mm Rat. The slightly larger bore of the 6mm gives a significant advantage over .224 caliber bullets, and if the velocity is there then you don’t have much to lose.

For those who dont already know, the MDRX is a multi-caliber ambidextrous bullpup rifle. Its closest peers are rifles like the Steyr AUG, the IWI X95 or T7, but the MDRX brings to the table a few more advantages. The MDRX will allow the use of both large and small frame cartridges, something the others will not do. Not only can the MDRX change between an assortment of calibers, but it can also be swapped in minutes with a single hex-key wrench. At the time of writing this, I have seven different barrels or conversion kits for my MDRX, they vary incredibly in their purpose and use. For cheap plinking, there is the traditional 223 (available in 16 or 20 inch barrels), for subsonic shooting there is the 16 inch 300Blk, for heavy thumping you can run the 308 Win (16 or 20 inch), and for distant shooting, you can run the 20 inch 6.5 Creedmoor. These four are available from the factory, I also have several custom barrels for my MDRX; the 450 Bushmaster brings devastating power to this tiny rifle. The 350 Legend is another that fits more of a niche hunting purpose, and today’s subject, the 6mm ARC is my latest addition to the collection. The 6 ARC brings inexpensive accuracy to the MDRX, it’s almost like a hybrid of my 223 barrel and 6.5 Creedmoor. It is inexpensive to load and shoot, has very negligible recoil, but shoots like a 6.5 Creedmoor as far as drop, and wind deflection. And the fact that it shoots so accurately makes this conversion kit perhaps my most favorite in the group, it rivals my SRS A1 as far as accuracy is concerned. Watch the video at the bottom of this article

So why the 6MM ARC?
Small frame autoloading rifles already have untold options when it comes to caliber, so what makes the ARC different? According to Hornady there are several reasons. The first one I’ll mention is performance, the ARC produces a similar if not superior ballistic curve than 308 Winchester. It maintains velocity and drop further than the 308 Win. It does this while showing off the second reason, efficiency. The ARC uses smaller, lighter cartridges with lighter powder charges to obtain this superior ballistic advantage. It also maintains a higher level of energy on target than it’s small frame competitors, the hundred-plus grain bullets carry a better energy load than your typical 69 to 90-grain bullets fired from AR’s. The overall load carried by a shooter or soldier is also less because of the ARC’s smaller size and weight when compared to larger cartridges like the 308. This reduction in weight, and powder charge also reduces the recoil felt by the shooter. This allows for rapid hit/miss confirmation and quick follow-up shots.

Of course, all this only matters if the ARC can shoot accurately. For me only accurate rifles are interesting, so I was happy to see how the ARC performed both on paper up close, and out at distance. The very first time I shot the 6 ARC at an actual range, I put three shots onto an IPSC target at 200 yards without even zeroing my scope.

After a little bit of research and some thought, I decided I would have an ARC of my own. Hornady shows a litany of manufacturers on their website that chamber rifles in the 6mm ARC, but I wanted to try something else.
My Desert Tech MDRX is a perfect candidate for a cartridge like the ARC, it is a multi-caliber platform that is easily adapted to large or small frame cartridges.
My good friend and talented gunsmith Eric at ES-Tactical got ahold of a quality 6mm barrel blank, and we set to working. The twenty-inch 7.5 twist barrel came from K&P, it was drilled, chambered, fluted, and threaded. With the appropriate barrel extension and gas block installed, all I needed was a bolt. The ARC uses a slightly larger bolt face than the 223, which took a little steady machining but worked perfectly. I also had to machine a little bit off of the 308 ejection chute clip in order to get it to firmly hold the smaller 6ARC cases.

The ARC runs at similar pressures to its peers, so I used the same gas settings as a 308 Winchester. And in a matter of a few minutes, the 6mm ARC roared to life.

Range trip
As I mentioned above, the first actual range trip for the ARC was impressive. The MDRX had been zeroed for my 223 barrel, but the POI was very close for the ARC. So close in fact, I shot 200, 450, and 550 yards without even zeroing the scope. Shooting standard size IPSC steel targets is not record breaking accuracy or anything, but it felt good right out of the gate.
Its fairly well known that the Grendel doesn’t like to feed well and doesn’t from 556 magazines, and the ARC shares that family trait. But I temporarily tried some P-mags until I got the proper magazines.  The 300BLK magazines worked better than 556 mags, but only if you loaded a few. I used a couple different magazines from Dura-Mag to avoid feeding issues. With these purpose-built magazines, you can load them up full, and have flawless function, like any other AR-type magazine.

ten and twenty round 6.5 Grendel magazines from Dura Mag worked flawlessly with the ARC

Recoil on the ARC is as Hornady suggested, minimal. Seeing your own hits on steel targets is easy at medium range, and even easier at long range.

A good five-shot group from the 6ARC at 100 yards

The accuracy of the ARC is superb, very likely due to the quality barrel and machining. But no doubt that the cartridges design also aids in keeping my groups together. Both factory Hornady match ammunition as well as my handloads performed well, producing groups that averaged around .5-.75 MOA and some of the best groups have been in the .3 to .4 MOA.
I was very impressed, it seemed to be the most consistent shooting barrel I have for this rifle. I was using my US Optics TS8X, which is significantly less magnification than I typically use when shooting groups. The RBR reticle is calibrated for 5.56 ammunition, but I figured it would be close with the 6 ARC. After shooting a few five-shot groups, I reached out to 300 yards across a canyon on a rock that was about ten inches wide. After hitting it over and over, I figured it was worth trying something further, but the only other target-sized rock I could find was at 960 yards. Not having a drop chart made yet, I did a little guestimating on my holdover. I was close, but shot over it with an 8 MRAD hold. So I dropped to 7 MRAD, and made a better windcall, and sent a second shot, which found my point of aim with nearly perfect precision. I was more than dazzled, as I continued to place shots on targets all over the mountain.

Loading the ARC
I’ve been handloading for many years, so loading the 6mm ARC was as simple as switching out some dies. The powder charges were pleasantly light, I used both CFE556 and BLC-2 for the ARC. Both performed well and provided good accuracy and consistency over CCI BR4 primers. I followed the load data that Hornady has available on their website, around 28 grains of powder was where I settled. The Hornady 105 grain BTHP was the bulk of my loading fodder, it is not too expensive, and performs very well. We have since used the ARC in a deadly encounter with some Wyoming antelope.

I’m usually slow to jump on new trends, it took me some time to pickup even the 6.5 Creedmoor. But this little cartridge has definitely piqued my interest, so much in fact I haven’t used any other barrels in my MDR since I got this one. Its accurate, smooth shooting, easy to spot hits and misses. And it hits targets pretty hard even at some significant distances, the only drawback I can even come up with is that I need to keep close tabs on the brass. Its a little more hard to come by than the average case, so I gotta keep an eye on them.

This awesome little cartridge is staying right close to me, we’ll be taking it hunting this fall for sure. And I don’t think it will be going away soon.
New things aren’t always better, but in the case of the 6MM ARC, I think Hornady has hit a 10X.


Watch the viedo to see the 6 ARC MDRX in action

The Desert Tech MDRX

Advancing technologies have made every part of the firearm and shooting industry better, with new materials, better production equipment, and a growing competitive market all driving forward it is no wonder that so many new and exciting products are available today. Desert Tech has been pushing those limits since its inception in 2007, and this year they have released another great product that follows the Desert Tech adage Tomorrow’s Weapons.

The MDRX is the next generation rifle from Desert Tech, it builds on the already popular MDR rifle they released in 2016. The MDRX is a short-stroke piston operated semi-automatic bullpup, for those who don’t know already, a bullpup is a rifle configured such that the action, magazine, and firing mechanics are all located behind the trigger. The purpose of this design gives the MDRX a shorter overall length than conventional rifles of the same barrel length. When you add in the other additional features of the MDRX the difference becomes even more apparent.

All Desert Tech rifles are designed with modularity in mind, and as such, they are all available as multi-caliber chassis and barrel combinations. The MDRX shares that same heritage, as it stands at the moment it is available in four different calibers from the factory; 223 Wylde, 308 Win, 300 BLK, and 6.5CM. All four of these barrel conversion kits can be interchanged in the same chassis, making the MDRX one of the few modern sporting rifles to accept both large and small frame calibers. All this from an SBR sized weapon without the stamp.
Being a semi-auto bullpup adds some challenges when it comes to universality, these challenges were overcome with ingenuity. The MDRX is completely ambidextrous, all of its controls are mirrored on both sides of the rifle for both right and left-handed shooters. In addition to the ambi controls, the rifle has a forward ejecting system that sends spent brass casing forward away from the shooter. Previous bullpup designs eject brass to the right side, which in a bullpup is a bad thing if you are left-handed. The MDRX can be fired from the right or left side with no concern of catching hot brass to your face. And if you are a dedicated left-hand shooter, you can swap ejection from forward right to forward left in just a few seconds.
The MDRX comes standard with a compensator made by Desert Tech called The Ratchet, the compensators are caliber specific to provide the best performance in recoil reduction and to stop muzzle rise.
One of the major challenges with bullpups is creating a good clean trigger pull, this is due to the linkage required to connect trigger shoe to the sear pack. This is another challenge that was overcome with design ingenuity, and the resulting trigger feel of the MDRX is widely accepted as great. Of the many people who have pulled the trigger on an MDRX, the common consensus is that it is a good trigger, not just for a bullpup, but a good trigger period.
The MDRX has a six-position adjustable gas valve allowing the operator to tune the rifle to whatever ammunition they might use, as well as use the rifle with a suppressor and a lower gas setting.
The MDRX’s aluminum/polymer chassis construction features full-length upper Picatinny rail, M-LOK slots for accessories and flush-mounted QD sling cups on the rear of the receiver. It is also designed to accept most AR-15 style magazines, and for large frame calibers, it uses SR-25 pattern mags. The rifle ships with caliber appropriate P-mags from Magpul.
The various caliber conversions for the MDRX feature popular twist rates, and standard barrel thread for adding muzzle accouterments. There are also both sixteen-inch, and twenty-inch barrels available in several of the assorted calibers, giving shooters different performance options. And with different barrel lengths, there are two different handguard lengths to go along.
The ambidextrous charging handles of the MDRX are non-reciprocating, they are normally locked to the front in a spring-loaded detent. They can also be locked to the rear by pulling them back and up, the release is as simple as slapping either of the handles down, and the bolt carrier closes into battery. The gun locks open upon firing the last shot from the magazine, the bolt release is centrally located right behind the magwell. This allows for very quick reloads by simply extending the thumb when seating a fresh magazine, thus closing the bolt on a fresh round. This actually can make reloading faster than most AR-style rifles due to fewer steps in the reload process.
The forward ejection system is perhaps the most curious of all the MDRX’s features. The open-faced bolt extracts the spent case and carries it to the rear, as the carrier travels it engages the ejector with a dovetail lug on either side. The momentum of the carrier then pulls the scissor-like ejector out, and it swipes across the open bolt face pushing the spent case off and into the ejection chute opposite. There it is retained by a spring-loaded pawl until the bolt carrier again travels forward where a protruding lug pushes the spent case forward and out the ejection chute. It’s a very interesting system, the only flaw I found with it is that when unloading an unspent cartridge from the rifle, it does require a firm stroke of the charging handles to get the cartridge seated firmly in the ejection chute. This is not so much a flaw as much as it is a training practice needed to be followed. The ejection system is designed to be used on either side of the rifle, both the ejector and chute can be swapped from one side to the other in seconds.

The MDRX SE utilizes a standard side ejection system

Also new for 2020 is a new side ejecting MDRX, for those who prefer a simpler, more traditional ejection pattern. The side eject is available in. 223 Wylde only, and can also be swapped from right to left side ejection. There is also the added benefit of a lighter overall weight, and a less expensive price tag.

On the Range
With several barrels in hand, I took the MDRX into my mountain hide to test its function. I started out shooting with the sixteen-inch 308 Win barrel, and loaded with Fiocchi 150 Grain FMJ ammunition at one hundred yards. After zeroing the sights, I fired a few five-shot groups, which ended up being around two MOA in size.
I continued firing the rifle at several additional targets to see how it ran. I found the recoil to be much softer than the previous similar rifles I had shot, this surely had much to do with the Ratchet compensator. The trigger was very clean and crisp, the reset is quite audible, I attribute that to the highly conductive poly receiver who’s hollow construction makes a very resonant chamber. I fired several additional groups using additional ammunition types as well, American Eagle XM80 as well as some 168 Grain match ammo from both Hornady and Federal. The match grade ammo certainly provided better groups, they averaged right around one MOA.

The MDRX seen with 20 inch 6.5CM barrel and longer handguard

So with several hundred rounds through the rifle, and a respectable shooting and zeroed rifle, I figured it was time to test the metamorphosis of this multi-caliber gifted rifle. The barrel is removed from the MDRX using a five-millimeter hex wrench, the rifle comes with one, but I prefer to use the suggested eighty-inch-pound torque limiter. After removing the handguard via two loosened screws and one take-down pin, the barrel is released by loosening the two barrel clamp screws by about one turn, and then disengaging the barrel lock 180 degrees to allow the barrel to slide out the front of the chassis. The bolt must be locked open to the rear to complete this operation. I then installed the twenty-inch 6.5 Creedmoor barrel, seating it firmly towards the breach. The process is then reversed, turning the barrel lock 180 degrees, and then torquing the two barrel clamp screws to 80 inch-pounds with a torque limiter. Followed by re-installing the handguard, which I had swapped out for the longer one. The rifle had just transformed from a sixteen-inch 308 Winchester into a twenty-inch 6.5 Creedmoor, and I was excited to see the increased performance. The point of impact would not be the same from one barrel to the next, but it was on paper at one-hundred yards, so it only took some minor corrections.
The 6.5 Creedmoor shot very well, with 140 Grain ammunition from both Hornady and Desert Tech, the groups averaged much better, in the sub to half MOA realm. With this kind of accuracy, I couldn’t wait to take the MDRX out to more significant distances.

For several hours the rifle neatly piled up brass right in front of my shooting mat, the rifle never malfunctioned, and just kept eating magazine after magazine of ammunition. I also fired some S&B 140 grain ammo through the rifle without any problems, I would have liked to try some lighter loads like a 120 grain, but I didn’t get the chance.

A typical 5 shot group from the MDRX 223 Wylde 40 Grain Fiocchi (100 Yards)

The rifle is easily swapped to smaller caliber barrels as well, the 223 Wylde and 300 Blackout do require a little more though.
A change of the bolt, a magwell spacer, and a swap of the ejection chute are required in addition to the barrel change.
The 223 Wylde shot just as good as the 6.5 Creedmoor, sub MOA groups were easy when shooting good ammo.

The great performance of the MDRX was hard to deny, it is a very compact rifle, with incredible reach, and good accuracy. Desert Tech has upped the game with this rifle, and they stand behind all their rifles with a lifetime warranty. It would be a great rifle whether you are hiding in a tree stand, need a behind the seat truck gun, or anywhere you’d need heavy firepower in a compact package. Its larger calibers are certainly useful for big game hunting and some distant shooting, while the smaller calibers are great for quick target shooting in a 3-gun style competition or varmint hunting. The MDRX carries a higher than average price tag, but that is because it brings so much more to the table. The multicaliber option alone actually saves money by consolidating your training, and less money spent on optics and accessories. You literally could do almost every American shooting activity with this one rifle. Whether it is a home defense rifle or a suppressed ranch rifle, the MDRX is a do-all rifle if ever there was one.


A 350 Legend for the MDR

Have you ever thought that maybe there is such a thing as too many guns? or too many barrels in some of our cases? Well if you did, you’re in the wrong place my friend. With so many terrible things going on in the world today, I like to embrace every new opportunity to shoot something. And since I have a good friend who is part mad-scientist part gunsmith, I get the opportunity almost as often as most see Bloomberg for president ads.
Watch the video at the end of this article
Once again Eric at ES Tactical has made me another barrel for my Desert Tech MDR, and this one is chambered in the new cartridge from Winchester, the 350 Legend.

The MDR with its barrel and optic collection is a do everything rifle

I’m no ballistician, nor does Winchester give me any kind of compensation, so I’ll just use their words and description of the 350 Legend. The Legend was specifically built as a hunting cartridge, a straight-walled hunting cartridge with a specific reason. Some state agencies only allow straight-walled cartridges for hunting big game, I assume this is because of the dangers of shooting beyond your line of sight in a semi-populous area. Winchester markets the Legend as the fastest straight-walled cartridge available, there are several factory loads with muzzle velocities over 2400 feet per second. They claim this gives the 350 Legend more speed than a 450 Bushmaster, more penetration than a 243, all while carrying more energy than common rounds like the 30-30 or 223.

350 Legend cartridges featuring Winchester’s 145 grain FMJ

Now that I’ve given the Winchester speech, I’ll tell you about the MDR conversion kit from ES Tactical. The multi-caliber MDR (or MDRX is the new model) is easily changed from one caliber to the next, the 350 Legend is the latest option from ES Tactical. The Legend uses the 223 Remington bolt, and magwell, but it has a Legend specific magazine due to its straight-walled design. The barrel I received from ES Tactical is eighteen inches long, it was threaded 5/8-24 to fit my suppressor, and fluted to save weight and impress the ladies. The barrel drops into my MDR chassis like any other, and after a quick gas valve adjustment, it was running smoothly.
I fired a couple different loads from both Winchester and Federal. The Winchester white box was their 145 grain fmj, while it shot just fine, it failed to impress me as far as accuracy and function. It even popped one primer out of a case which made me suspicious. The Federal Premium 180 grain Power Shock performed much better, both for function as well as accuracy. The 350 Legend was everything a deer hunter would need inside the suggested 250 yards it is recommended for, I found hitting jug sized targets boringly easy from the standing position, even at the 250-yard line. This may in part be due to the MDR’s bullpup balance, and the quality of barrel and trigger.

The 18 inch 350 Legend barrel outside the MDR chassis

For those who are still in the dark about the MDR(X), you really should do yourself a favor and check it out, it is multi-caliber, completely ambidextrous, and its bullpup configuration gives it an extremely compact chassis while carrying big options for both distance and accuracy. If your interested, you can read more about it here or there.
The 350 Legend does not like the 223 Remington ejection chute on the MDR, though they share the same case head, the lack of a bottleneck on the Legend causes a bind in the chute causing jams. The 308 sized chute won’t hold the case, so it’s no-go as well. That’s fine, just as with my 450 Bushmaster, I leave the chute off and let it throw the spent cases to the side. I did pay close attention to where they were landing though, as I intend on reloading them, and the MDR throws them pretty far.

Both the 450BM and the 350L would be great for those of you who are forced by government caveat to hunt with them, for me, I guess it would depend on whether I wanted to hunt supersonic or subsonic. Either way, I don’t think you could go wrong.